Mammoth Memory

Difference between DNA nucleotides and messenger RNA (mRNA) nucleotides.

There is an important difference between the bases used in DNA nucleotides and messenger RNA (mRNA) nucleotides. While DNA bases pair as follows:

There is a difference between DNA base pair and mRNA pair

The bases in mRNA pair like this:

The difference is that the Uracil nucleotide replaces Thymine to tell the cell to treat it differently to DNA

That is U (Uracil) replaces the T (thymine)

This is so that the cell can tell that the messenger RNA (mRNA) is to be treated differently to DNA.

The messenger RNA (mRNA) now floats away from the DNA and is small enough to pass out of the nucleus and into the cytoplasm of the cell.

Because of the base change mRNA can leave the nucleus to the cytoplasm

In the cytoplasm there are transfer RNA (tRNA) which have three permanent bases attached. These bases are in combinations of A, U, C, G.

The cytoplasm contains transfer RNA which have 3 permanent bases attached which are combinations of A U C and G

These transfer RNA (tRNA) pick up one of 20 amino acids which correspond to the permanent base combinations and therefore look like:

The transfer RNA picks up one of the twenty amino acid that corresponds to the permanent bases

The ribosome attaches itself to the messenger RNA (mRNA).

Ribsomes contained in the cytoplasm attaches itself to the mRNA strand

The messenger RNA (mRNA) is then read by the ribosome three bases at a time.

The ribosome reads the mRNA 3 bases at a time and attaches free floating tRNA to the 3 bases

The next transfer RNA (tRNA) moves along onto the messenger RNA (mRNA) in the ribosome producing a chain of amino acids.

tRNA moves along the mRNA amino acids start to join in the ribosome

The transfer RNA (tRNA) break away leaving the amino acid in the chain.

Amino acid chains form as the ribosome moves along the mRNA attaching tRNA as it goes

The amino acids form a chain which is known as a protein, in this case a haemoglobin protein.

As the ribosome nears the end of the mRNA it has made a long chain of protein in this case haemoglobin

The amino acid chain, when complete, breaks away from the ribosome. 

At the end of the mRNA the protein chain breaks away from the ribosome

Once released the amino acid chain folds into a complex 3D shape depending on the protein that has been built.

The protein chain then folds and forms a complex 3D shape depending on the protein that has been built

Here the amino acid chain folds into a Haemoglobin protein. Haemoglobin proteins carry the oxygen in our red blood cells.

The newly formed haemoglobin protein carries oxygen in red blood cells

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